Cessna 172R, Operating Handbook

Page: 445 / 500

CESSNA
MODEL 172R
SECTION
9
-
SUPPLEMENTS
SUPPLEMENT
15
-
FAA APPROVED
3.
Flashing GS
--
Indication of a flagged glideslope. (GS will
rearm automatically if a valid GS signal is received.)
NOTE
To continue tracking
the
localizer,
observe the
appropriate minimums for a nonprecision approach.
(Press ALT twice in rapid succession
to
terminate the
flashing. Control the pitch axis in the default VS mode.)
NOTE
At the
onset
of mode
annunciator flashing, the autopilot
has already reverted
to
a default mode of operation, i.e.,
ROL and or VS mode.
An immediate
attempt to
reengage
to
lost mode may be made if the
offending
navigation, glideslope or compass flag has cleared.
EXCEPTION
The HDG annunciation will
flash for 5 seconds upon
selection
of NAV, APR,
or REV
modes
to
remind the
pilot
to set
the HDG bug for use as course datum.
Effects of instrument losses
upon
autopilot operation:
1
.
Loss
of
the
artificial
horizon
--
no effect on the autopilot.
2. Loss of the
turn
coordinator
--
autopilot inoperative.
3.
Loss of the Directional Gyro (DG)-- The directional gyro
does
not
provide any
system
valid flag. If the DG fails
to function
properly the autopilot heading and navigation
mode will
not
function correctly. Under these conditions, the only
usable
lateral mode is ROL.
4. Loss of Horizontal Situation Indicator (HSI) (if installed)
--
If
the HSI fails
to function
properly the autopilot heading and
navigation mode will
not
function correctly. Under these
conditions, the only usable lateral mode is ROL.
5. Loss
of
Blind Altitude Encoder
--
Altitude Alerter and Altitude
Preselect
function inoperative.
Original
Issue
S15-19